1. Field of the Invention
The present invention relates generally to the field of motion picture cinematography, and more specifically to algorithmically reducing the interaxial separation for stereo-pair motion picture or video cinematography to produce lower parallax values.
2. Description of the Related Art
In stereoscopic cinematography, two planar cameras are employed to capture two perspective views, one for each eye. A stereoscopic camera has two camera heads—one for producing a left perspective, and the other for producing a right perspective. The strength or quality of the stereoscopic image is, to a large extent, determined by the separation of the two cameras, or the interaxial separation. The farther apart the camera heads, in other words, the greater their interaxial (distance between lens axes) separation, the stronger the stereoscopic effect. Conversely, the closer the camera heads, the weaker the stereoscopic effect.
In the art of stereoscopy, screen parallax is defined as a measure of the distance between left and right corresponding or homologous image points when such points are projected on a screen. It is usually important when shooting stereoscopic images to be sure that the maximum parallax values will, in a typical viewing configuration, not exceed a certain limiting value—namely the average or mean human interpupillary separation for background points. If the value of parallax is too great, discomfort is experienced because the user's eyes are forced to diverge, an experience that does not happen in the visual field when not observing a stereoscopic projected image. A principal way to control the value of parallax is through the adjustment of the camera's interaxial separation, t.
Adjustability of the interaxial separation enables the cinematographer to control the strength of the stereoscopic image. The proper interaxial value must be used to produce a natural-looking image, and the distance of the object from the cameras bears on the interaxial value and hence the quality of the image. One might suspect that stereoscopic photography ought to be done with an interaxial separation that is equal to the interpupillary separation, but this does not always produce the best results. Selecting the interpupillary separation may be a good starting point, but there are so many exceptions that this rule of thumb is frequently violated, and good quality viewing may be experienced when the cameras are closer or further apart than the interpupillary separation.
Thus adjustability of the camera rig can be highly beneficial. Rigs have been designed with different features. For example, one previous rig seeks to reduce the camera interaxial separation to approximate the human interpupillary distance. Such a design presents limitations with respect to the reduced interaxial separations that can be achieved. Another design shoots into or through a beam splitter or pellicle. This design results in a large rig generally unsuitable for many kinds of photography. In the case of both rigs, highly precise and time-consuming mechanical/optical alignment is required.
It would be beneficial to provide a stereoscopic photographic system and method that reduces or eliminates the interaxial separation and parallax problems associated with previous designs or camera rigs that offer adjustable interaxial separation values. Such a design may provide improved functionality over devices exhibiting those negative aspects described herein.